The jamb liner is a rigid component of a window which is installed vertical to a window frame on the left and right of two window sashes. The function of the jamb liner is to house a spring-loaded balance system in an enclosed track. The spring supports the weight of the sash and allows the window to open and close. Each sash has its own set of tracks which allows the sash, with the assistance of the balance system, e.g., spring loaded balance system, to move up and down. The sashes are integrated with the balance system via a set of pivot bars. The pivot bars allow the sash to rotate, subsequently locking the balance system in place.